CN116093332B - High-nickel positive electrode material, preparation method thereof and lithium ion battery - Google Patents

High-nickel positive electrode material, preparation method thereof and lithium ion battery Download PDF

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CN116093332B
CN116093332B CN202310362432.6A CN202310362432A CN116093332B CN 116093332 B CN116093332 B CN 116093332B CN 202310362432 A CN202310362432 A CN 202310362432A CN 116093332 B CN116093332 B CN 116093332B
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positive electrode
electrode material
boric acid
solid
nickel
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CN116093332A (en
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易亮
谭铁宁
朱高龙
华剑锋
李立国
戴锋
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Sichuan New Energy Vehicle Innovation Center Co Ltd
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Sichuan New Energy Vehicle Innovation Center Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • Battery Electrode And Active Subsutance (AREA)

Abstract

The application provides a high-nickel positive electrode material, a preparation method thereof and a lithium ion battery, and relates to the technical field of lithium ion batteries. The preparation method of the high-nickel positive electrode material comprises the following steps: mixing the anode material matrix with boric acid solution, and carrying out solid-liquid separation to obtain a solid separation product; sintering the solid separation product to obtain the high-nickel anode material; after the solid-liquid separation, the moisture content in the solid separation product is 3-15 wt%. The lithium ion battery provided by the application comprises the high-nickel positive electrode material. Through using boric acid solution to mix with the positive electrode material matrix, on the one hand, residual alkali on the surface of the positive electrode material matrix can be removed, and on the other hand, boric acid can be contacted with primary particles in the material, so that after solid-liquid separation, the solid-liquid separation is carried out, the solid-liquid separation is directly sintered, lithium borate is coated in the interior and the surface of the prepared high-nickel positive electrode material, the discharge capacity of the material is improved, and the electrochemical performance of a battery is further improved.

Description

High-nickel positive electrode material, preparation method thereof and lithium ion battery
Technical Field
The application relates to the technical field of lithium ion batteries, in particular to a high-nickel positive electrode material, a preparation method thereof and a lithium ion battery.
Background
In recent years, new energy automobile technology is developed day by day, and the energy density of lithium ion power batteries is increasingly required. The high-nickel ternary positive electrode material has stable electrochemical performance (higher charge and discharge capacity, good multiplying power performance and wider electrochemical window) and good safety performance, and gradually becomes a main stream positive electrode material in the power battery market. However, the high nickel cathode material has a high surface alkali content due to a low sintering temperature during the production process, and the material needs to be washed to reduce the surface alkali content.
The electrochemical performance of the positive electrode material obtained after common water washing is reduced to a certain extent, so that the surface of the material after water washing is generally required to be coated and modified, and the electrochemical performance of the positive electrode material is improved. At present, most positive electrode material manufacturers use water for washing and then carry out drying, and then carry out dry coating modification, so that the process flow is longer, and the material after washing is not sintered, so that the mechanical processing performance of the material is reduced to a certain extent; in particular, in the dry coating process, the material fine powder is further increased, and the self-discharge of the positive electrode material is deteriorated. Therefore, the process method for reducing residual alkali on the surface of the positive electrode material, realizing surface coating and optimizing the self-discharge performance of the positive electrode material is found, and has important significance.
Disclosure of Invention
The application aims to provide a high-nickel positive electrode material, a preparation method thereof and a lithium ion battery. Compared with the dry coating process, the boric acid solution is adopted for water washing and coating, so that the process flow is reduced, and the production cost is reduced.
In order to achieve the above object, the technical method of the present application is as follows:
the application provides a preparation method of a high-nickel positive electrode material, which comprises the following steps:
mixing the anode material matrix with boric acid solution, and carrying out solid-liquid separation to obtain a solid separation product;
sintering the solid separation product to obtain the high-nickel anode material;
after the solid-liquid separation, the moisture content in the solid separation product is 3-15 wt%.
Preferably, the preparation method satisfies at least one of the following conditions:
a. the chemical general formula of the positive electrode material matrix is Li a Ni b Co c Mn d O 2 The method comprises the steps of carrying out a first treatment on the surface of the Wherein a is more than or equal to 1.01 and less than or equal to 1.06,0.8, b is more than or equal to 0.9,0.05 and c is more than or equal to 0.18,0.02, d is more than or equal to 0.15, and b+c+d=1;
b. the surface of the positive electrode material matrix contains residual alkali;
c. before the positive electrode material matrix is mixed with the boric acid solution, the method further comprises the following steps: and crushing the positive electrode material matrix.
Preferably, the preparation method further satisfies at least one of the following conditions:
d. the ratio of the mass of the positive electrode material matrix to the mass of water in the boric acid solution is 1: (0.5-1.5);
e. the mass of boric acid in the boric acid solution is 0.01-5% of the mass of the positive electrode material matrix;
f. the positive electrode material matrix, when mixed with the boric acid solution, comprises: adding the positive electrode material matrix into the boric acid solution, and stirring for 5-20 min;
g. the sintering process is performed in an oxygen-containing atmosphere.
Preferably, the solid-liquid separation mode comprises suction filtration.
Further preferably, the time of the suction filtration is 3 min-10 min, and the negative pressure intensity during the suction filtration is minus 0.01MPa to minus 0.06MPa.
Preferably, the sintering process comprises: heating to 120-600 ℃ according to the heating rate of 1-10 ℃/min, and preserving heat for 8-15 h.
The application also provides a high-nickel positive electrode material, which is prepared by adopting the preparation method of the high-nickel positive electrode material.
Preferably, the secondary particle surface of the high nickel positive electrode material is coated with lithium borate, and the primary particle surface inside the secondary particle is also coated with lithium borate.
Preferably, the minimum particle diameter Dmin of the high-nickel positive electrode material is more than or equal to 1.5 mu m.
The application also provides a lithium ion battery, which comprises the high-nickel anode material.
The application has the beneficial effects that:
the preparation method disclosed by the application is simple to operate, less in process flow, low in cost and suitable for large-scale industrial production. The boric acid solution is used for mixing with the positive electrode material matrix, so that residual alkali on the surface of the positive electrode material matrix can be removed, and on the other hand, the solution is used for wet mixing, so that boric acid is in contact with primary particles in the positive electrode material matrix, after solid-liquid separation, the solid separation product is heated from room temperature in the process of directly sintering without a drying procedure, the evaporation of water in the solid separation product is slower, boric acid is less volatilized, and boric acid left on the surface and the inside of the positive electrode material matrix can react with lithium-containing substances, so that the inside and the surface of the finally prepared high-nickel positive electrode material are both coated with a layer of lithium borate, and the modification treatment of the positive electrode material is realized.
Compared with the minimum value of the particle size of the material particle prepared by the dry coating, the minimum value of the particle size of the high-nickel positive electrode material prepared by the preparation method is larger, so that the self-discharge of the positive electrode material is effectively reduced, and the discharge capacity is improved.
Compared with the positive electrode materials prepared by using dry coating and other processes in other batteries, the lithium ion battery has improved battery capacity, initial efficiency and other electrochemical properties.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope of the present application.
FIG. 1 is a TEM image of primary particles at the surface position of secondary particles of the high nickel cathode material prepared in example 1;
FIG. 2 is a TEM image of primary particles inside secondary particles of the high nickel cathode material prepared in example 1;
FIG. 3 is a TEM image of primary particles at the surface position of secondary particles of the high nickel cathode material prepared in comparative example 2;
FIG. 4 is a TEM image of primary particles inside secondary particles of the high nickel cathode material prepared in comparative example 2;
fig. 5 is a primary particle TEM image of the inside of the secondary particles of the high nickel cathode material prepared in comparative example 4.
Detailed Description
The term as used herein:
"prepared from … …" is synonymous with "comprising". The terms "comprising," "including," "having," "containing," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, step, method, article, or apparatus. The conjunction "consisting of … …" excludes any unspecified element, step or component.
When an equivalent, concentration, or other value or parameter is expressed as a range, preferred range, or a range bounded by a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. For example, when ranges of "1 to 5" are disclosed, the described ranges should be construed to include ranges of "1 to 4", "1 to 3", "1 to 2 and 4 to 5", "1 to 3 and 5", and the like. When a numerical range is described herein, unless otherwise indicated, the range is intended to include its endpoints and all integers and fractions within the range.
In these examples, the parts and percentages are by mass unless otherwise indicated.
"parts by mass" means a basic unit of measurement showing the mass ratio of a plurality of components, and 1 part may be any unit mass, for example, 1g may be expressed, 2.689g may be expressed, and the like. If we say that the mass part of the a component is a part and the mass part of the B component is B part, the ratio a of the mass of the a component to the mass of the B component is represented as: b. alternatively, the mass of the A component is aK, and the mass of the B component is bK (K is an arbitrary number and represents a multiple factor). It is not misunderstood that the sum of the parts by mass of all the components is not limited to 100 parts, unlike the parts by mass.
"and/or" is used to indicate that one or both of the illustrated cases may occur, e.g., a and/or B include (a and B) and (a or B).
After the water washing and drying process is adopted, the process flow of preparing the positive electrode material by using the dry coating is longer, and the performance of the prepared positive electrode material is not well improved, so that the dry coating is gradually changed into the wet coating in the follow-up research. This is mainly because the wet coating is more uniform than the dry coating and the residual alkali amount on the surface of the high-nickel positive electrode material after washing is reduced, so that the coating material is enriched only in a partial region of the surface of the positive electrode material due to non-uniformity during the dry coating, thereby affecting the normal deintercalation of lithium ions. In addition, the wet coating can penetrate into the surface of the primary particles at the inner part of the secondary particle sphere, so that after sintering, a coating layer is likely to be formed on the surface of the primary particles, thereby accelerating the speed of lithium ion deintercalation, reducing the contact area of the positive electrode material and the electrolyte, and being effective even after the secondary particle sphere is split. However, the dry coating can only form coating on the surface of the secondary particle sphere, and the internal positive electrode material after the sphere is cracked or broken can be directly contacted with the electrolyte, so that the side reaction of the positive electrode material and the electrolyte is accelerated.
However, when using the boric acid solution for wet coating, the inventors found that in most processes, after the boric acid solution and the cathode material are subjected to water washing coating, a drying process is used, and the material is generally dried in a drying oven, but the temperature rising rate of the drying oven at a low temperature is relatively high, and no oxygen or air atmosphere is introduced during drying, so that the boric acid cannot react with the lithium-containing substance, and when the material is dried, a large amount of moisture on the surface and in the material is rapidly evaporated, and part of the boric acid is carried away along with the evaporation of the moisture, so that the boric acid finally coated on the surface of the material is reduced, and the risk of exhaust emission is aggravated. Meanwhile, boric acid brought by aqueous solution among primary particles in the material can be carried to the surface of the material along with rapid evaporation of water, so that the final boric acid can only be coated on the surface of the material, and partial material cracking and even breaking can be caused when the material is instantaneously contacted with high temperature. These reasons all result in the performance of the final wet coated cathode material not being very improved.
After further investigation, the present inventors found that after washing filtration with boric acid solution and drying, if the filtered material is low in moisture, a large amount of dissolved lithium and boric acid is taken away while the filtered water is split, and if the filtered material is high in moisture, lithium and boric acid are lost due to instantaneous high temperature in the subsequent drying process. If the moisture of the dried material is low, the loss of boric acid is serious; if the moisture of the dried material is higher, the drying process is meaningless, and a great deal of resources and time are wasted. In this regard, the inventor provides a process method by fully considering the important influence of water after washing, filtering and drying on boric acid coating, and by strict water control, the loss of lithium and boric acid is reduced, and the waste of resources is greatly avoided.
The application provides a preparation method of a high-nickel positive electrode material, which comprises the following steps:
s1, mixing a positive electrode material matrix with a boric acid solution, and carrying out solid-liquid separation to obtain a solid separation product;
s2, sintering the solid separation product to obtain the high-nickel anode material.
Of particular note is that the moisture content in the resulting solid-separated product after solid-liquid separation is 3wt% to 15wt%, and may be, for example, 3wt%, 5wt%, 8wt%, 10wt%, 12wt%, 15wt%, or any value between 3wt% and 15wt%.
In some alternative embodiments, the positive electrode material matrix described in S1 has the chemical formula Li a Ni b Co c Mn d O 2 . Wherein a is more than or equal to 1.01 and less than or equal to 1.06,0.8, b is more than or equal to 0.9,0.05 and c is more than or equal to 0.18,0.02, d is more than or equal to 0.15, and b+c+d=1.
In some alternative embodiments, the surface of the positive electrode material matrix in S1 contains residual alkali. Specifically, the positive electrode material matrix can be an initial high-nickel positive electrode material obtained by mixing and sintering a ternary precursor and a lithium source, wherein the sintering is the first sintering, and the surface of the obtained positive electrode material matrix contains a large amount of residual alkali.
In some alternative embodiments, prior to mixing the positive electrode material matrix with the boric acid solution, further comprising: and crushing the positive electrode material matrix. This is mainly to ensure that the residual alkali on the surface of the positive electrode material substrate sufficiently reacts with and is removed from the boric acid, and at the same time, the boric acid solution can sufficiently infiltrate into the inside of the secondary particles of the positive electrode material.
In some alternative embodiments, the ratio of the mass of the positive electrode material matrix to the mass of water in the boric acid solution in S1 is 1: (0.5 to 1.5), for example, 1:0.5, 1:0.8, 1:1. 1:1.2, 1:1.5 is either 1: (0.5 to 1.5).
In some alternative embodiments, the mass of boric acid in the boric acid solution in S1 is 0.01% to 5% of the mass of the positive electrode material matrix, and may be, for example, any value between 0.01%, 0.1%, 0.5%, 1%, 3%, 5%, or 0.01% to 5%.
In some alternative embodiments, the positive electrode material matrix in S1, when mixed with the boric acid solution, comprises: and adding the positive electrode material matrix into boric acid solution, and stirring for 5-20 min. In the stirring process, residual alkali on the surface of the positive electrode material matrix can react with boric acid and be dissolved in the solution, and the residual alkali can be effectively removed after subsequent solid-liquid separation.
In some alternative embodiments, the means for solid-liquid separation in S1 comprises suction filtration. Compared with the material obtained by common filtration, the water content on the surface is too high, and then the material is sintered after the drying treatment, the water content of the material obtained by final suction filtration can be controlled by using the suction filtration mode, and then the sintering treatment can be directly carried out, so that the process flow is reduced, and the production cost of the high-nickel anode material is reduced.
Further preferably, the negative pressure at the time of suction filtration is from-0.01 MPa to-0.06 MPa, and may be, for example, from-0.01 MPa to-0.02 MPa, from-0.03 MPa to-0.04 MPa, from-0.05 MPa to-0.06 MPa, or any value between-0.01 MPa and-0.06 MPa.
The time required by suction filtration is 3-10 min. Particularly, in the suction filtration process, if the color of the filtrate is not colorless and transparent, it indicates that the positive electrode material enters the filtrate, the suction filtration is needed to be performed again at the moment, after the suction filtration is completed, the moisture content in the positive electrode material obtained by the suction filtration is needed to be tested, if the moisture test is qualified, that is, the moisture content in the suction filtration product is between 3wt% and 15wt%, the sintering in the S2 can be performed, and if the moisture test is not qualified, the suction filtration is continued.
In some alternative embodiments, the sintering process in S2 is performed in an oxygen-containing atmosphere. Specifically, boric acid coated on the surface of the positive electrode material matrix reacts with lithium-containing substances under the action of oxygen to generate lithium borate.
In some alternative embodiments, the sintering process in S2 further comprises: the temperature may be raised to 120℃to 600℃at a temperature-raising rate of 1℃to 10℃per minute, for example, 1℃per minute, 3℃per minute, 5℃per minute, 8℃per minute, 10℃per minute, or 1℃per minute to 10℃per minute, and then the temperature may be raised to 120℃to 600℃at 150℃to 200℃to 300℃to 500℃to 600℃or 120℃to 600℃for 8 hours to 15 hours, for example, 8 hours, 10 hours, 12 hours, 14 hours, 15 hours, or 8 hours to 15 hours.
The application also provides a high-nickel positive electrode material, which is prepared by adopting the preparation method of the high-nickel positive electrode material. The surface of the secondary particles of the prepared high-nickel positive electrode material is coated with lithium borate, and the surface of the primary particles positioned in the secondary particles is also coated with lithium borate.
In some alternative embodiments, the high nickel positive electrode material is produced with a minimum particle size Dmin of 1.5 μm or more.
In the preparation method, the process of washing and drying and then carrying out dry coating is abandoned, boric acid solution is directly added in the washing process, the washing and coating are put in the same process, the production process flow is shortened, a large amount of cost is saved, the drying process is eliminated, and the possibility of producing micro powder in the drying process is avoided, so that the minimum particle size of the prepared high-nickel positive electrode material is higher than that of the material prepared by the dry coating.
The application also provides a lithium ion battery, and the high-nickel anode material prepared by the preparation method is used in the anode of the lithium ion battery.
Embodiments of the present application will be described in detail below with reference to specific examples, but it will be understood by those skilled in the art that the following examples are only for illustrating the present application and should not be construed as limiting the scope of the present application. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
Example 1
The embodiment provides a high-nickel positive electrode material, which uses a boric acid water washing coating process, and the specific preparation method comprises the following steps:
(1) 100g of pure water is weighed and placed in a beaker, 0.6g of boric acid is weighed and poured into the pure water for full dissolution, and the ternary precursor and the lithium source are sintered and crushed to obtain the finished Li 1.05 Ni 0.83 Co 0.11 Mn 0.06 O 2 100g of positive electrode material matrix is added into boric acid aqueous solution, a glass rod is used for stirring for 15min, the mixture is poured into a suction filtration device for suction filtration after stirring is completed, the suction filtration time is 5min, the negative pressure is-0.02 Mpa, whether filtrate is colorless liquid or not is observed in the suction filtration process, and if black exists, the experiment needs to be carried out again because the positive electrode material matrix enters the filtrate. In this example, a macro Hua Yiqi SHZ-D (III) model suction filtration apparatus (hereinafter referred to as "filter apparatus") was used.
(2) And (3) after the suction filtration is finished, carrying out a moisture test, wherein the moisture content is qualified between 3% and 15%, transferring the materials into a sagger for paving and sintering if the materials are qualified, and continuing the suction filtration if the materials are unqualified. During sintering, the temperature is increased to 550 ℃ at 5 ℃/min, and the sintering is carried out for 10 hours under the condition that oxygen is adopted as the sintering atmosphere. And obtaining the high-nickel anode material coated with boric acid after sintering.
The embodiment also provides a lithium ion battery, which is prepared by the following steps:
the high nickel positive electrode material prepared in the embodiment, conductive carbon black and PVDF are mixed according to the following ratio of 18:1:1, then evenly mixing the materials by using NMP as a solvent, coating the mixture on an aluminum foil, drying the mixture at 80 ℃ to obtain a positive pole piece, assembling the positive pole piece into a power button cell, and then carrying out a power button assembly test with the test voltage of 2.8-4.3V.
Example 2
The present example provides a high nickel positive electrode material using boric acid water washing coating process, and the specific preparation method is the same as that of example 1, except that in step (2), during sintering, the temperature is raised to 280 ℃ at 5 ℃/min, and sintering is performed for 10 hours.
The embodiment also provides a lithium ion battery, and the specific preparation process is the same as that of embodiment 1.
Example 3
The present example provides a high nickel positive electrode material using a boric acid water washing coating process, and the specific preparation method is the same as that of example 2, except that 4g of boric acid is weighed in step (1).
The embodiment also provides a lithium ion battery, and the specific preparation process is the same as that of embodiment 1.
Comparative example 1
The comparative example provides a high nickel positive electrode material, which uses a water washing non-coating process, and the specific preparation method comprises the following steps:
(1) Weighing 100g of pure water, placing into a beaker, sintering the ternary precursor and a lithium source, and crushing the Li 1.05 Ni 0.83 Co 0.11 Mn 0.06 O 2 Adding 100g of positive electrode material matrix into pure water, stirring for 15min by using a glass rod, pouring into a suction filtration device for suction filtration after stirring is completed, wherein the suction filtration time is 5min, the negative pressure is-0.02 Mpa, observing whether filtrate is colorless liquid or not in the suction filtration process, and carrying out experiments again if black exists (the positive electrode material matrix enters the filtrate).
(2) And (3) after the suction filtration is finished, carrying out a moisture test, wherein the moisture content is qualified between 3% and 15%, transferring the materials into a sagger for paving and sintering if the materials are qualified, and continuing the suction filtration if the materials are unqualified. During sintering, the temperature is increased to 550 ℃ at 5 ℃/min, and the sintering is carried out for 10 hours under the condition that oxygen is adopted as the sintering atmosphere. And (5) after the sintering is finished, obtaining the high-nickel anode material which is not coated by water washing.
Comparative example 2
The comparative example provides a high nickel cathode material, which is prepared by a water washing and drying process and a dry coating process, and the specific preparation method is the same as that of comparative example 1, except that the high nickel cathode material is dried in an oven at a drying temperature of 120 ℃ for 2 hours after the suction filtration in the step (2). And controlling the water content to be between 0.1 and 0.3 percent after drying, transferring to agate for grinding after passing, adding 0.6g of boric acid, grinding until no obvious bright point exists, and transferring to a sagger for paving and sintering. During sintering, the temperature is increased to 550 ℃ at 5 ℃/min, and the sintering is carried out for 10 hours under the condition that oxygen is adopted as the sintering atmosphere. And after sintering, obtaining the high-nickel anode material coated by the water washing dry method.
Comparative example 3
The comparative example provides a high nickel cathode material, which is prepared by using a dry coating process after washing and drying, and the specific preparation method is the same as that of comparative example 2, except that the temperature is raised to 280 ℃ at 5 ℃/min during sintering in the step (2), and the sintering is performed for 10 hours.
Comparative example 4
The comparative example provides a high nickel cathode material using a boric acid water washing coating drying process, and the specific preparation method is the same as that of example 1, except that in step (2), after the suction filtration is completed, the cathode material is sent to an oven for drying, the drying temperature is 120 ℃ and 2 hours are carried out. And controlling the water content to be between 0.1 and 0.3 percent after drying, transferring the mixture into a sagger for paving and sintering after the mixture is qualified, and continuing drying if the mixture is unqualified.
The results of the electrochemical performance tests of the cells prepared in examples 1 to 3 and comparative examples 1 to 4 are shown in Table 1.
TABLE 1
Comparing the test results in table 1, it can be seen that: in comparative example 1, only the washing and sintering processes were used, and the electrochemical properties of the fabricated battery were the worst of examples and comparative examples because the surface of the positive electrode material was not coated. In comparative examples 2 to 3, however, the electrochemical performance of the cells produced by the water washing, drying and dry coating process was lower than that of the cells produced by the boric acid water washing and coating process of examples 1 to 2. In contrast, comparative example 4 was compared with example 1, and the electrochemical performance of the finally produced battery was significantly lower than that of example 1 by subjecting comparative example 4 to drying treatment after suction filtration, which indicates that the drying treatment after suction filtration significantly affects the coating effect of lithium borate.
Primary particle TEM images of the surface and the inside of the secondary particles of the positive electrode material prepared by the boric acid water-washing wet-coating of example 1 are shown in fig. 1 and 2, respectively. Fig. 3 and 4 show TEM images of primary particles on the surface and inside of the secondary particles of the positive electrode material prepared by the dry-washed-dry-coated process of comparative example 2. Fig. 5 shows a primary particle TEM image of the inside of the secondary particles of the positive electrode material prepared in comparative example 4. The comparison picture is clearly visible: the primary particles of fig. 1 and 2 have a uniform coating layer on the surface; the coating film layer appears at a part of the surface of the primary particles in fig. 3, and the coating film layer is not present at a part of the surface; the primary particle surfaces in fig. 4 and 5 are completely free of the coating film.
Comparative example 2 the coating material was concentrated only in a partial region of the surface of the positive electrode material due to the non-uniform process characteristic after the dry coating, so that the phenomenon of fig. 3 occurred, and the dry coating hardly caused the coating material to enter the inside of the secondary particles, so that the coating film did not appear on the surface of the primary particles inside the secondary particles, as shown in fig. 4. In comparative example 4, since boric acid between primary particles in the secondary particles was lost by evaporation of moisture due to drying treatment before sintering treatment, no coating film was formed on the surfaces of the primary particles in the secondary particles after sintering.
The preparation method of the application is characterized in that after solid-liquid separation is carried out on the boric acid water washing solution, the material is directly sintered without a drying process, so that the material is slowly heated from room temperature, the water evaporation is slower, the loss of boric acid is less, the inside and the surface of secondary particles of the high-nickel positive electrode material are coated with a layer of lithium borate after sintering, and the electrochemical performance of the battery is improved.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the application.
Furthermore, those skilled in the art will appreciate that while some embodiments herein include some features but not others included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the application and form different embodiments. For example, any of the above-described claimed embodiments may be used in any combination. The information disclosed in this background section is only for enhancement of understanding of the general background of the application and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

Claims (6)

1. The high-nickel positive electrode material is characterized in that the surfaces of secondary particles of the high-nickel positive electrode material are coated with lithium borate, and the surfaces of primary particles in the secondary particles are also coated with lithium borate;
the preparation method of the high-nickel positive electrode material comprises the following steps:
mixing and stirring the anode material matrix and the boric acid solution for 15min, and carrying out solid-liquid separation to obtain a solid separation product;
sintering the solid separation product to obtain the high-nickel anode material;
the surface of the positive electrode material matrix contains residual alkali;
before the positive electrode material matrix is mixed with the boric acid solution, the method further comprises the following steps: crushing the positive electrode material matrix;
the mass of boric acid in the boric acid solution is 0.01-5% of the mass of the positive electrode material matrix;
after the solid-liquid separation, the moisture content in the solid separation product is 3-15 wt%;
the sintering process comprises the following steps: heating to 550 ℃ according to the heating rate of 1-10 ℃/min, and then preserving heat for 10h;
the sintering process is carried out in an oxygen-containing atmosphere;
the minimum particle diameter Dmin of the high-nickel positive electrode material is more than or equal to 1.5 mu m.
2. The high nickel positive electrode material according to claim 1, wherein the positive electrode material matrix has a chemical formula of Li a Ni b Co c Mn d O 2 The method comprises the steps of carrying out a first treatment on the surface of the Wherein a is more than or equal to 1.01 and less than or equal to 1.06,0.8, b is more than or equal to 0.9,0.05 and c is more than or equal to 0.18,0.02, d is more than or equal to 0.15, and b+c+d=1.
3. The high nickel positive electrode material according to claim 1, wherein a ratio of a mass of the positive electrode material base to a mass of water in the boric acid solution is 1: (0.5-1.5).
4. The high nickel positive electrode material according to claim 1, wherein the means for solid-liquid separation comprises suction filtration.
5. The high nickel anode material according to claim 4, wherein the suction filtration time is 3-10 min, and the negative pressure during the suction filtration is-0.01 MPa to-0.06 MPa.
6. A lithium ion battery, wherein the lithium ion battery comprises the high nickel positive electrode material according to any one of claims 1 to 5.
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CN112186156A (en) * 2020-09-24 2021-01-05 惠州亿纬创能电池有限公司 Water washing method of high-nickel cathode material, product thereof and application of product
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CN115498171A (en) * 2022-11-03 2022-12-20 湖北融通高科先进材料有限公司 High-nickel ternary cathode material and preparation method and application thereof
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CN112133897A (en) * 2020-09-17 2020-12-25 陕西红马科技有限公司 Method for reducing surface alkali amount of positive electrode material and improving electrochemical performance through wet coating
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